<!DOCTYPE html>
<html class="reftest-wait">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Update timeline range on reversed animation refTest</title>
<link rel="help" src="https://drafts.csswg.org/scroll-animations-1/#named-timeline-range">
<link rel="match" href="./animation-update-ref.html?translate=60px">
<script src="/web-animations/testcommon.js"></script>
</head>
<style type="text/css">
  @keyframes anim {
    from { transform: translateX(100px) }
    to { transform: translateX(0px) }
  }
  #scroller {
    border:  1px solid black;
    overflow: hidden;
    width: 300px;
    height: 200px;
  }
  #target {
    margin-bottom: 800px;
    margin-top: 800px;
    margin-left: 10px;
    margin-right: 10px;
    width: 100px;
    height: 100px;
    z-index: -1;
    background-color: green;
    animation: anim auto linear;
    animation-timeline: --timeline;
    view-timeline: --timeline;
  }
  #target.exit-range {
    animation-range-start: exit 0%;
    animation-range-end:  exit 100%;
  }
</style>
<body>
  <div id="scroller">
    <div id="target"></div>
  </div>
</body>
<script type="text/javascript">
  document.documentElement.addEventListener('TestRendered', async () => {
    runTest();
  }, { once: true });

  async function runTest() {
    await waitForCompositorReady();

    const anim = target.getAnimations()[0];
    // If animation-duration:auto is not supported, getAnimations() may not
    // return this animation.
    if (typeof anim !== 'undefined') {
      anim.playbackRate = -1;

      // Scroll to exit 60%.
      scroller.scrollTop = 860;
      await waitForNextFrame();

      // Update the animation range.
      target.classList.add('exit-range');
      await waitForNextFrame();
    }

    // Make sure change to animation range was properly picked up.
    document.documentElement.classList.remove("reftest-wait");
  }
</script>
</body>
</html>
